Master's Dissertation
DOI
10.11606/D.3.2008.tde-01042008-100452
Document
Author
Full name
Sidinei Colodeti Cristo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2008
Supervisor
Committee
Martorano, Marcelo de Aquino (President)
Isore, Alain Jean
Mourão, Marcelo Breda
Title in Portuguese
Modelagem matemática da condução de calor transiente e quase-estacionária no processo de refusão por eletroescória.
Keywords in Portuguese
Fornos de refusão por eletroescória
Simulação da solidificação
Abstract in Portuguese
Title in English
Quasi-steady and transient heat transfer mathematical model for electroslag remelting process.
Keywords in English
ESR
Mathematical modeling
Simulation
Solidification
Abstract in English
A mathematical model for heat transfer in the electroslag remelting process (ESR) was implemented using the transient heat conduction equation in cylindrical coordinates. The solution of the equations was facilitated by using a change of the axial coordinate, also known as the Landau transformation, which fixed the calculation domain size during the ingot growth period. Two analyses were carried out. In the first, a parametric study of the model was done, while in the second, the solidification of an industrial ingot was modeled. In the first analysis, the differential equation in dimensionless form indicated the important processing parameters, namely, the melting rate, the type of solidifying material, and the heat extraction to the mold. The effects of these parameters were examined on the pool profile geometry, local solidification time (LST) and length of ingot to reach quasi-steady state. The results showed that it is not possible to define, for all industrial conditions, a unique ratio of ingot length to ingot radius when the metal pool reaches the quasi-steady state. It was also observed that the Stefan number (Ste), which defines the type of solidifying material, had a negligible effect on the pool depth and on the LST for Ste > 0.5. In the second analysis, the model was used to simulate the solidification in the ESR process of an ingot made of the ASTM 138 steel. The geometric profile of the metal pool and the heat flux at the metal-mold interface were measured, showing reasonable agreement with the model results. Finally, the results given in the present work allow the definition (from a microstructural standpoint) of the optimum melting rate and the time to reach quasi steady-state for a wide range of industrial materials, ingot diameters and heat transfer conditions.